This project develops new labeling techniques generally applicable to the positron emitting radionuclides carbon-11 of fluorine-18. In the current proposal several areas are emphasized. These areas are: 1. The synthesis and evaluation of fatty acids labeled in 3 specific positions. 2. The evaluation of a new hypoxic imaging agent. 3. The development of new labeling agents involving carbon-11 labeled hypofluorite as a new synthon and new approaches to protein and peptide labeling of compounds with potential medical application.